How similar keywords match to search terms

Your ads are eligible to appear based on the similarity of your keywords to the search terms a person enters when they're searching on Google or our search partner sites. Only one keyword can trigger an ad per search term. Check out the examples below to learn what happens when multiple keywords in your account match a search at the same time.

Multiple keywords within the same ad group are similar to the search term

Within an ad group, you might have several similar keywords that match a search. For example, you might have the broad match keywords plumber course and plumber training course, which could both match the search term training course for plumber.

In this situation, the AdWords system uses a set of preferences to determine which of your keywords to use. The preferences rank approximately in the following order:

If you have a keyword that is identical to the search term, the system will prefer to use this keyword to trigger an ad. This is true even if there are other keywords in your ad group that are similar to the search term.

Example

Let's say the search term is plumber course and your ad group includes both the broad match keyword plumber course and phrase match keyword plumber. In this example, the system will prefer to use the broad match keyword plumber course because it matches the search term plumber course exactly.

If you have multiple keywords that are the same, the system will prefer to use the exact match keyword. For example, if the search term is plumber, and your ad group includes both the broad match keyword plumber and exact match keyword plumber, then the system will prefer to use the exact match keyword.

On rare occasions, the system will prefer to use a keyword that is cheaper -- meaning it has a lower cost-per-click (CPC) bid -- and has a higher Ad Rank.

Example

Let's say someone searches for plumber tool and your ad group includes the keywords plumber tools and plumber tool.

Keyword

Maximum CPC bid

Ad quality

Ad Rank

plumber tools

$0.10

high quality

16

plumber tool

$0.15

low quality

11

Usually, the keyword plumber tool would be preferred because it matches the search term more closely than plumber tools. However, plumber tools is cheaper, higher quality, and has a higher Ad Rank. Therefore, the system will prefer showing plumber tools in this instance. Keep in mind that Ad Rank is calculated every time your keyword matches a search term and your ad is entered into an ad auction.

Multiple keywords within multiple ad groups are similar to the search term

When multiple ad groups have keywords that match a search term, the AdWords system must make a more complex decision. This is because different ad groups might have different ads, landing pages, and campaign settings. All of these differences can result in different experiences for customers, and can result in different Quality Scores for similar keywords in different ad groups.

In this situation, the AdWords system uses a set of preferences to determine which of your keywords to use. The preferences rank approximately in the following order:

If one keyword is identical to the search term, the system will prefer to use that keyword to trigger an ad, regardless of the ad group the keyword is in. This is true even if there are other ad groups with keywords similar to the search term.

Example

Let's say the search term is plumber course. If one of your ad groups includes the broad match keyword plumber course, while another ad group includes the phrase match keyword plumber, then the system will prefer to use the broad match keyword because it matches the search term exactly.

If you have multiple ad groups with keywords that are the same, the system will prefer to use the exact match keyword.

Example

Let's say the search term is local plumber. If one of your ad groups includes the broad match keyword localplumber, while the exact match keyword local plumber is in a different ad group, then the system will prefer to use the exact match keyword.

In this example, the system will prefer plumber course because it has a higher Ad Rank.

Note

In rare cases, the keyword with the highest Ad Rank might seem to be less relevant to a particular search term than other eligible keywords. Because higher relevance is generally correlated with a higher Ad Rank, this should happen infrequently. Try running a search terms report to see instances in which the less relevant keyword triggers your ad. Then, add that search term as a negative keyword to the ad group that includes the less relevant keyword.

Exceptions to preferences

The AdWords system has some exceptions that might apply to all of the preferences listed above. The exceptions to the preference rules shown above might occur for the following examples:

Your campaign's daily budget can affect each of the scenarios listed above. If a keyword is in a budget-restricted campaign, which means that the campaign's budget isn't high enough to accrue all possible traffic, the keyword won't always be able to trigger an ad even if it otherwise could. This helps prevent the campaign from greatly exceeding its budget. Learn more about how you can avoid a depleted daily budget.

Example

Here's an example of how a budget-restricted campaign could affect the use of keywords when multiple keywords are the same but have different match types.

Let's say your campaigns are called "Clogged Sinks" and "Broken Water Heater." In your "Clogged Sinks" campaign, you have the exact match keyword plumber, and in your "Broken Water Heater" campaign, you have the broad match keyword plumber.

All else being equal, the exact match keyword in your "Clogged Sinks" campaign would trigger an ad when someone searched for the term plumber because it's the more restrictive match type. However, if your "Clogged Sinks" campaign were budget-restricted, then the exact match keyword in this campaign would sometimes be unable to trigger an ad. This means the broad match keyword in your "Broken Water Heater" campaign would trigger an ad instead.

On rare occasions, the system will prefer to use a keyword that is cheaper -- meaning it has a lower cost-per-click (CPC) bid -- and has a higher Quality Score and a higher Ad Rank.

Example

Let's say someone searches for plumber tool and you have the keywords plumber tools and plumber tool with the following maximum cost-per-click (max CPC) bid, Quality Score, and Ad Rank:

Keyword

Maximum CPC bid

Quality Score

Ad Rank

plumber tools

$0.10

7

0.7

plumber tool

$0.15

4

0.6

Usually, the keyword plumber tool would be preferred because it matches the search term more closely than the keyword plumber tools. However, the keyword plumber tools is cheaper and has a higher Quality Score and a higher Ad Rank. Therefore, the system will prefer to show the keyword plumber tools.

Note

In rare cases, the keyword with the highest Ad Rank might be less relevant to a particular search term than other eligible keywords. Because higher relevance is generally correlated with a higher Ad Rank, this will happen infrequently. Try running a search terms report to see instances in which the less relevant keyword triggers your ad. Then, add that search term as a negative keyword to the ad group that includes the less relevant keyword.

If an account contains an excessive number of instances of the same keyword (think well more than dozens of identical instances), automated systems will pare down the number of matching keywords. Then, we'll apply the preferences discussed above. For example, if you have 5,000 instances of the keyword plumber tool in your account, the system will pare down the number of keywords. Then, we'll use the set of preferences described above.